the Dattatreyayogasastra, a Sanskrit text on yoga composed in about 1200 CE in South India. It teaches four types of yoga practice but devotes the majority of its 193 verses to hathayoga, which it divides into two varieties, one which consists of the eight auxiliaries first taught by Patanjali and one which has nine physical methods. It is thus the first text to combine the astanga system of Patanjali with physical techniques, and its teachings were highly influential on later authors and commentators of yoga texts. The book is addressed primarily to scholars but will also be of interest to students and practitioners of yoga.